Field of the Invention
The present disclosure relates to a thin and light-weighted package for a power storage device, such as, e.g., a battery and a capacitor for use in a mobile device including, e.g., a smartphone and a tablet terminal, a battery or an electric condenser for use in, e.g., a hybrid vehicle, an electric vehicle, wind power generation, solar power generation, or nighttime electric power, and also relates to a power storage device externally covered by the package.
In this disclosure, the term “aluminum” is used to include the meaning of both aluminum and its aluminum alloys unless otherwise specifically defined.
Description of the Related Art
The following description of related art sets forth the inventor's knowledge of related art and certain problems therein and should not be construed as an admission of knowledge in the prior art.
In recent years, in accordance with thinning and weight saving of a mobile electric device, such as, e.g., a smart phone and a table terminal, as a packaging material for a power storage device, such as, e.g., a lithium ion secondary battery, a lithium polymer secondary battery, a lithium ion capacitor, and an electric double layer capacitor, which are to be loaded on such a mobile electric device, in place of a conventional metallic can, a laminated body made of a heat-resistant resin layer/an adhesive layer/a metal foil layer/an adhesive layer/a thermoplastic resin layer (See Japanese Unexamined Patent Application Publication No. 2005-22336, hereinafter referred to as “Patent Document 1”) has been used. Normally, the laminated body is subjected to stretch forming or deep drawing into a three-dimensional shape such as an approximately rectangular parallelepiped shape. Further, an electric power source for an electric vehicle, and a large-size electric power source or capacitor used to store electric power, etc., are often packaged by the laminated body (package) of the aforementioned structure.
In the meantime, in the aforementioned mobile electrical device, etc., in recent years, a further thinning and weight saving have been developed. As a power storage device to be mounted thereon is required to be thinned and light-weighted. In accordance with this, developments have been made to attain the thinning and weight saving of a package for a power storage device. Currently, using an aluminum foil having a thickness having no possibility of pinhole generation or having a thickness thicker than that, the package is structured. It is known that as the thickness decreases, there is a possibility that pinholes are generated in an aluminum foil, and as the thickness decreases, the number of pinholes increases. In cases where there exist pinholes, the aluminum foil cannot fulfill a function as a barrier layer, which causes problems that an intrusion of moisture from an outside cannot be prevented and diffusion or leakage of electrolyte cannot be prevented. For this reason, an aluminum foil cannot be further decreased in thickness.
Further, as to a thermoplastic resin layer (heat-sealable resin layer) as an inner layer, if the layer is further reduced in thickness than a current level, it becomes difficult to secure a sufficient heat seal strength.
Therefore, for a product having the aforementioned structure as a fundamental structure, it was difficult to attain further thinning and weight saving.
Further, in a conventional structure, it requires about one week to age (cure) an adhesive agent after dry lamination, and therefore it has been required to attain shortening of the production time.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present disclosure. For example, certain features of the preferred described embodiments of the disclosure may be capable of overcoming certain disadvantages and/or providing certain advantages, such as, e.g., disadvantages and/or advantages discussed herein, while retaining some or all of the features, embodiments, methods, and apparatus disclosed therein